Thousands of victims of the 9/11 attacks appealed to the Supreme Court today, asking it to overturn a lower court decision barring lawsuits against Saudi Arabia for supporting acts of terrorism.

The petition contended that U.S. intelligence agencies had unearthed ample evidence of the Saudi Arabia government's providing tens of millions of dollars to Islamist charities that in turn funded Osama bin Laden and his al-Qaeda organization.

U.S. government officials had repeatedly warned Saudi officials in the 1990s that government-backed charities were providing money and logistical support to bin Laden, but they failed to do anything about it, the petition said.

The appeal was filed by the Philadelphia law firm of Cozen O'Connor, which is representing dozens of U.S. insurers that paid $5 billion in property-damage and other claims stemming from the attacks on the World Trade Center. It seeks to overturn a finding by the U.S. Court of Appeals for the Second Circuit in Manhattan in August that U.S law bars lawsuits against Saudi Arabia for allegedly financing terrorism.

The ruling said, in part, that Saudi Arabia could not be sued because it had not been designated a terrorism supporter by the U.S. State Department.

"Saudi officials knew of al-Qaeda's use of terrorism, including its intent and practice of targeting U.S. citizens and interests, well before Sept. 11, 2001," the law firm said in papers filed today. "The uncontested allegations and evidence establish that the charities are dominated and controlled by the kingdom."

Lawyers for the kingdom, as well as leading Saudi officials, have denied the lawsuit's allegations.

Cozen, which is taking the lead in the case, was joined in the appeal by firms representing thousands of victims of the attacks and their relatives, lawyers for other insurance companies, and the Port Authority of New York and New Jersey.

Cozen sued Saudi Arabia, senior members of the Saudi royal family, and several Islamist charities in 2003, nearly two years to the day after the attacks, alleging that charities controlled by the Saudi government had been the primary source of funding for bin Laden, and that U.S. and European officials had repeatedly warned the Saudis that the charities were bankrolling al-Qaeda and other terror groups.

The lawsuit cites hundreds of U.S. government intelligence findings, along with information unearthed by the law firm itself.

"If you believe, as we do, that the U.S. will be subject to future terrorist attacks, that means that [under the second circuit ruling] you will have absolutely no redress against the people who committed those acts, unless they were designated state sponsors of terrorism," said Stephen Cozen, the lead lawyer for the plaintiffs.

The appeal, Cozen added, "raises hugely important errors of law made by the second circuit."

As a general rule, getting the Supreme Court to accept an appeal is a long shot. It typically hears only about 5 percent of the 1,000-plus requests that are filed with it each year. It tends to accept cases in which lower courts have issued conflicting opinions in an effort to create uniform law.

"The court looks at whether there is a conflict among the circuits [among other issues]," said Nancy Winkelman, an appellate lawyer with Schnader, Harrison, Segal & Lewis of Center City. "The role of the Supreme Court is to make uniform law."

Cozen O'Connor engaged one of Washington's top appeals attorneys, Carter Phillips, of the firm of Sidley Austin, for assistance in the case.

The world of Supreme Court lawyers in Washington is small and rarified. Chief Justice John Roberts was one of them before he served on the D.C. Circuit Court of Appeals and then the Supreme Court. Saudi Arabia and other defendants in the lawsuit also have as counsel top appellate lawyers, including Michael Kellogg, of Huber, Hansen, Todd, Evans & Figel, and William H. Jeffress, of Baker Botts, the law firm of former Secretary of State James Baker.

The Second Circuit relied heavily on its reading of the Foreign Sovereign Immunities Act in finding in August that Saudi Arabia could not be sued. The law, passed in 1976, establishes general immunity from lawsuits for foreign governments, but also provides exceptions including commercial disputes and instances in which foreign government officials commit harmful acts that are outside the scope of normal governmental activities.

The central dispute in the litigation is an amendment added by Sen. Frank Lautenberg (D., N.J.) in 1996 that permits U.S. citizens to sue foreign governments for acts of terrorism, so long as those governments have been designated terrorism supporters by the U.S. State Department.

The second circuit found that Saudi Arabia could not be sued because the State Department had not designated it a terrorism supporter.

Yet Cozen lawyers argued in their petition that Congress had intended for the so-called terrorism exception to apply to acts of terrorism outside the United States, and that it had never intended to restrict lawsuits by U.S. citizens for violent acts that occurred domestically, such as 9/11.

They cite two notorious cases involving state-sanctioned assassinations in which survivors sued foreign governments and U.S. courts upheld the lawsuits.

In one, survivors of Orlando Letelier, a former Chilean ambassador to the United States killed in a car bombing, were permitted by a federal judge in Washington to sue the Chilean government after evidence produced in a criminal investigation showed government officials were involved in the plot.

In the other, the widow of Henry Liu, a Chinese journalist and critic of the Taiwanese government, was permitted to sue by the U.S. Court of Appeals for the Ninth Circuit after evidence emerged that her husband had been slain by gang members at the direction of a senior Taiwanese government official.

Contact staff writer Chris Mondics at 215 854 5957 or cmondics@phillynews.com.